Silk screen printing apparatus improvement



Feb. 14, 1961 c. D. BLACK SILK SCREEN PRINTING APPARATUS IMPROVEMENT Filed March 26, 1956 3 Sheets-Sheet 1 Feb. 14, 1961 c. D. BLACK SILK SCREEN PRINTING APPARATUS IMPROVEMENT 3 Sheets-Sheet 2 Filed March 26, 1956 INVENTOR. d/ax'e/rce a 5/404 A ORA/EX Feb. 14, 1961 c, [BLACK 2,971,629

SILK SCREEN PRINTING APPARATUS IMPROVEMENT Filed March 26, 1956 3 Sheets-Sheet 3 INVENTOR.

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United States Patent SILK SCREEN PRINTING APPARATUS IMPROVEMENT Clarence D. Black, Hickman Mills, Mo., assignor to Injection Molding Company, Kansas City, Mo., a corporation of Missouri Filed Mar. 26, 1956, Ser. No. 573,908

7 Claims. (Cl. 198-24) This invention relates to machines for silk screen printing of oval, molded plastic containers and refers more particularly to an improved means for handling the containers in the silk screen printing area, said improved handling means greatly facilitating and speeding up the printing process and the insertion and withdrawal of containers into and from the printing area.

Previously, machines have been provided for the silk screen printing of the surface of oval molded or blowmolded bottles of plastic material such as polyethylene. A conventional machine comprises a base frame, a screen rack of rectangular shape having a silk screen mounted in the floor thereof and adapted to receive printing ink thereon mounted relative said frame, a resilient swab of vertically up and down relative the rack'in and out of contact with the silk screen, means for moving the rack horizontally from a starting position relative said swab whereby to periodically force ink through the screen in a printing step and timing means to coordinate the motions of the rack and swab relative one another so the swab is down in said printing step to contact the screen and up away from the screen for a recovery step wherein the rack returns to its original starting position.

Means must be provided to position a container relative the silk screen and, as the screen moves across with the rack under the swab in the printing step, move the oval container in an are along with the motion of the screen to receive on successive areas of the container the ink forced through the screen by the swab. Previously, such container positioning means have comprised only'a single orificed clip adaptable to receive a single container which (1) is charged by hand in a pause on one side of the screen, (2) swings across a limited arc in the printing step, (3) pauses on the other side of the screen after the printing step where the container is removed by hand, (4) returns uncharged with the rack and screen in a recovery step and, (5) is charged again, etc. Such a manipulation of the containers to be printed in the screening process is slow, inaccurate, requires excessive human action in a small area, does not utilize the full capacity of the machinery, is prone to permit errors of the operator which result in smearing of the ink on the printing container and, finally, is highly boring to the Additionally, for safety sake, the pauses for charging and removal either must be made sufliciently long to allow for the opeartors cumulative fatigue if automatic, or governed by the operator by foot operated release equipment or the like. High rates of production in such conventional devices are thus impossible.

Therefore, an object of the present invention is to pro- Vide improved means for handling the containers in/the 2,971,629 Patented Feb. 14, 1961 "ice screen printing area, said improved means greatly facilitating and speeding up the screen printing process and the insertion and withdrawal of the oval containers into and from the printing area.

Another object of the invention is to provide such an improved handling apparatus for receiving the containers in the screen printing area comprising a magazine rotatably mounted adjacent the printing area, said magazine having a plurality of oval bottle receiving cavities formed therein whereby to permit separate charging and discharging of bottles to said cavities.

Another object of the invention is to provide such a rotatable magazine having a plurality of bottle receiving cavities therein positioned adjacent the printing area and means to rotate said magazine a limited amount in a single direction in precise correspondence with the time and distance of the screen rack motion whereby to permit precise and accurate screen printing of the surface of the container, the rotating means converting the horizontal motion of the rack assembly to rotary motion of the magazine.

Another object of the invention is to provide such a rotatable magazine having a plurality of container receiving cavities formed therein and means to rotate said magazine a limited amount in a single direction together with means for automatically preventing over-shooting of the limited rotational motion of the magazine.

Another object of the invention is to provide such an improved means for handling the containers in the screen printing area including feeding means to position containers accurately adjacent said rotatable plural cavitied magazine in combination with fully automatic charging means to transfer said containers from said feeding means into' cavities of said magazine, said charging means being safe and positively feeding.

Another object of the invention is to provide means for handling containers to be printed in the screen printing area including fully automatic discharge means to eject printed containers from the cavities of such a rotatable magazine as previously described, such discharge means simultaneously operable with said charging means if such is desired. V

Yet another object of the invention is to provide improved means for'handling oval containers in the screen printing area wherein is provided in combination with discharge means, as previously described, fully automatic individual receiving means for each of said discharged containers, said means individually suspending for drying and subsequent handling each of said printed containers from the interior thereof whereby to fully protect the printed area on the container, said receiving means also having means for producing regular limited motion thereof to keep a fresh unloaded receiving means positioned opposite the discharge area of said magazine and bracing means to keep the receiving means properly aligned to receive the containers discharged from the cavities of the rotatable magazine.

Other and further objects of the invention will appear in the course of the following description thereof.

In the drawings, which form a part of the instant specification and are to be read in conjunction therewith, an embodiment of the invention is shown and, in the various views, like numerals are employed to indicate lik parts.

Fig. 1 is a front schematic view of the inventive oval container receiving magazine positioned under a conventional silk screen rack and its associated resilient swab,

invites the combination being shown at the beginning of the printing step, the swab being down in contact with the silk screen to force said screen against the surface of the magazine and the container positioned therewithin.

Fig. 2 is a view of the same combination of apparatus as in Fig. 1, this figure showing a later intermediate stage in the silk screen printing process started in Fig. 1 wherein the screen rack is moving horizontally relative the axis of the magazine and the stationary resilient swab, the magazine itself rotating simultaneously therewith whereby ink is transferred through the silk screen onto successive areas of the surface of the oval container.

Fig. 3 is a view similar, to those of Figs. 1 and 2 illu'se trating the end of the printing step when the horizontal motion and the rotatory motion of the rack and magazine respectively, have come to an end. 7

Fig. 4 is a view similar tothose preceding, illustrating the recovery step wherein the rack returns to its original starting position in horizontal motion as indicated by the arrow, the magazine remaining stationary around its axis while one cavity is filled with an unprinted container and another cavity is emptied of an already printed container. As may. be seen, the swab or squeegee has been lifted to avoid forcing of printing ink through the silk screen as the rack moves back to its starting position.

Fig. 5 is a view similar to those preceding it, illustrating a stage in the process at the end of the recovery step wherein the rack has returned to its starting position and its horizontal motion has ceased, the magazine has remained stationary around its axis, a new container has been charged into one of the vacant cavities and an older container has been removed from another said cavity after having been printed, the swab or squeegee still being in an elevated position, the stage in the process being such that lowering of the swab into contact with the screen willreturn the cycle to the stage shown in Fig. 1.

Fig.6 is a side View of a conventional silk screen printing apparatus with the inventive improved containerhandling means positioned relative thereto and is a view taken 'along lines 66 of Fig. 7 in the direction of the arrows.

Fig. 7 is a front view of the apparatus shown in Fig. 6 which is taken along the lines 77 of Fig. 6 in the direction of the arrows. I

Fig. 8 is a rear view of the apparatus shown in Figs. 6 and 7.

Fig. 9 is a view'taken along the lines 99of-Fig.6 in the direction of the arrows.

Fig. 10 is a view taken along the lines 10 10 of Fig. 6 in the directionof the arrows.

Fig. ll'is a view taken along the lines ll -ll of Fig. 6 in. the direction of the arrows.

1 Referring to the drawings, allof the "apparatus of the 'conventional silk screening device and the improvements thereon comprising theinstantinvention are mounted o'n a base frame having a horizontal table surface 20, upwardly extending support arms 21 anddownwardly extending legs 22. Crossbearns 23 support table relative legs 22. Upper and lower cross bars '24and 25 extend between arms 21 and are'fixed relative thereto by bolts 26 and 27. V I I v Rectangularscreen rack 28 has'silk screen 29 mounted relative one'side thereof. Ink block 29a is positioned at one side of said'screen. Cylindrical sheaths 30 and 31 encircle paired lower crossbars -25. Q Arms 32 and 33 connect the ends of sheaths 30 and 31st) they slide in concerthorizont ally on bars "25. Rack supporting arms 34 and 35 receive screen rack 28 therebetween andare connected to arms 32 and 33 by stub arms 36 and 37 which are each paired on each side of the-rack. -Hand screws 38 and 39 engage one end of the rack 28 through arm 34 to removably position the rack 28 therein. The above assembly'permits horizontal sliding motion of the rack 28 relative the base frame.

Means for providing limited to and fro horizontal-motion of the rack assembly comprise the pneumatic or oval containers with straight edge walls.

hydraulic cylinder 40 fixed to bracket 41 on side arm 21. Cylinder 40 has piston arm or plunger 42 extending therefrom fixed to arm 32 by nuts, one of which, 43, may be seen in Fig. 6. Pneumatic pressure lines 44 and 45 on cylinder 40 lead to conventional air or fiuid sources controlled by conventional timing means and valves (not shown) whereby the screen rack is movable from a starting position (Fig. 1, retracted piston arm 42) horizontally by plunger extension through a printing step for a limited distance, then returnable by retraction of the plunger 42 in a recovery step to said starting position.

A mass of printing ink 46 is shown positioned on the silk screen 29 in Figs. 1 through 5. Ink block 29a dams the ink 46 relative the squeegee 47.

A resilient swab or squeegee 47 is mounted relative silk screen 29 and movable vertically relativethereto to alternately contact said screen whereby to force ink through the screen for the printing operation when the rack moves horizontally in its printing step. Shaft 48 extends downwardly from pneumatic cylinder 49 and en-- gages bar 48a from which depending shafts 48b extend to engage the top of swab 47. Rearwardly extending arms 50 support pneumatic or hydraulic cylinder 49 relative crossbars 24 between upwardly extending side arms 21. Swab guides 51 prevent flexion of the pneumatic cylinder shafts'in the vertical up and down motion of the squeegee under the action of the pneumatic cylinder 49. Pneumatic flow lines 52 and 53 are connected to the cylinder 49 and provide the impetus to move the swab 47 upwardly and downwardly vertically relative said screen rack 28 (or the swab may be spring returned upwardly). Conventionai timing means to coordinate the motions of the rack and swab relative one another so the swab is down during the printing step motion of the rack and up for the recovery step motion of the rack are connected to said flow lines 52 and 53 and 44 and 45. Such timing means are not shown as they are conventional and may be any desired form such as mechanical, electrical, pneumatic, etc. Swab 47 is constructed of rubber or other resilient mate.- -rial so as not to damage the silk screen itself and to be resilient relative thereto in the back and forth horizontal motion of the rack 28.

Referring now to the inventive means for handling containers in the silk screen printing area and during the screen printing operation, a rotatable magazine 54 having a plurality of sized cavities 55 extending axially therethrough for receiving oval containers 56 to besilk screen printed on one side thereof is rotatably positioned underneath and adjacent said screen rack whereby to rotate relative the silk screen 29 in said previously described printing step. Magazine 54 is mounted on shaft 57 which extends .rearwardly therefrom. The magazine itself, as may be seen best from Fig. 6, is positioned directly under the screen rack 28 and silk screen 29. Referring to Fig. 9, it will be seen that the magazine is positioned so that its peripheral faces or the faces of the containers ,posi- -tioned therein will always be in contact with the silk screen 29 itself. The peripheral faces of the cavities-55 are at least partly open to expose the area of the container to'be printed. The magazines shown in cross section in Figs. 7, 9 and 1 through 5 are formed to receive It is also'contemplated that purely oval containers be printed wherein the edge walls thereof are rounded and the outwardly extending portions of the magazine'receiving therebetween the containers will slightly overlie the container face'to be printed and thus'more firmly wedge the containers :in the magazine and "prevent any outward movement thereof. In'containers and cavitiessuch as are shown'in -the figures, the containers must 'wedge themselves "fairly tightly between the edge faces of the cavities whereby to retain the containers 56 therein. The axial lengthfof the magazine is preferably not lessthan the length of the "container'to be printed. The ends of the'c'avitie's 55 opposite the input side for the containers into the rim mam ,77 is not fixed to the shaft.

magazinecavities may be at least-partly closed whereby the containers cannot be forced past that end of the magazine and will be fixedly positioned therein.

Means are provided preferably positioned on said table 20 for causing a limited rotation of the magazine 54 on shaft 57 relative the screen rack and screen 29 in said previously described printing step. It is evident from an inspection of Figs. 1 through 5, which illustrate .the printing and recovery steps of the screen rack relative the magazine in the printing step and the recovery of the screen rack, that the motion of the screen rack 28 is received in upwardly extending support arms '58, 59

and 60. Bearings 61 and-62 are fixed to-front and rear support arms 58 and 60, respectively, to permit smooth rotation of shaft 57 therein. Spacing rings 63 and64 are fixed to the shaft 57 by screws65 and 66, respectively, the, first spacing ring on the rearside of upwardly extending arm 59 and the second on the forward side of the rearmost support arm 60. Friction disc 67 is fixed to the endmost portion of shaft 57 by screw 68, the frie- 'tion disc itself being received in. friction cylinder 69 having opening 70 in the upper surface. thereof, the cylinder being fixed to the rearwardly extending. platform 71 by bolt 72 and having adjustment .bolt 73 therethrough, Ratchet disc 74 is fixed toth eshaftflsl by screw 75 and has four-station ratchet 76 on therearmost face thereof. Each of .the stations of. the .ratchet 76 correspond to a rest position of the magazine 54 rela- .ti ve the screen 29 in the screen rack 28. When one .of

.in Fig. 11, the magazine 54 is in the position shown in Fig. l. Spool 77 having recessed portion 78 is freely and rotatably mounted on the shaft 57 between the ratchet 76 and the spacing ring 64. Arms 79 and 80 extend rearwardly from horizontal arms 32 and 33 which engage slidable sleeves or cylinders 30 and 31. Arms 79 and 80 extend rearwardly and downwardly whereby the end portions thereof are opposite the ends of the screen rack 28 as is best seen in Fig. 8. Ringed screws 81 and 82 extend inwardly from the arms 79 and 80 and cord 83 is fixed at its ends thereto. The cord 83 loops over the recessed portion 78 of the spool 77 and 'frictionally engages'it whereby the spool 77 rotates when the screen rack moves horizontally. The cord 83 is positioned at the exact .level of the screen 29 and comes off the top surface of the recessed portion 78 of the spool in both directions tangentially. The spool 77 is,

preferably, in the recessed portion 78 thereof, exactly I Starting from a position as shown in Fig. 11, when the screen rack 28 moves horizontally in its printing step,

the spool 77 will be rotated by virtue of the cord 83 frictionally engaging the surface thereof. The pawl 84 will cause the ratchet 76 on engagement thereof to force rotation ofthe shaft 57 despite the fact that the spool When the screen rack 28 returns in its recovery motion to its original position, the spool 77 will rotate freely on the shaft while the .friction disc 67 will prevent any rotation of the shaft 57 .itself. The size of the pawl 84 relative the distance between stations on the ratchet 76 is such that the re- .turn movement of the screen rack 28 will cause the pawl .84 to; overshoot the next station on the ratchet 76,by a lmsas rsd am unt he by o. p o ide. positive engagement of the ratchet by the pawl 84 under the impetus of spring 86 on the next printing step motion of the screen rack. The friction disc 67 also prevents overshooting by the magazine-of its rotational motion at the end of the printing motion of the screen rack. By means of the arms 79 and 80 extending rearwardly opposite the spool 77, the ring screws 81 and 82 being positioned with the cord 83 at the same level, as the screen 29, and the recessed portion 78 of the spool being the same diameter as the magazine 54, the horizontal motion of the'screen rack 28 is translated into unidirectional rotational motion of the spool 77 and magazine 54 in the desired direction. of rotation with no shaft 57'rotation on the recovery step motion of the screen rack 28. Front support arm 58 is fastened to table 20 by bolt 87 and the two rear support arms 59 and 60 are fixed to 'the we of 'angled support base 88 having bolts 89 and 90 as seen in Fig. 8. i

Means are provided postioned relative said frame to feed unprinted containers to a position relative said magazine for charging thereinto. The means for feeding the containers relative the magazine preferably comprises a hollow channel 91 having an open end 92 and a closed end 93, an opening (not shown) in the side wall of the channel adjacent to the magazine of a size to permit expulsion of one of the oval containers therefrom and an opening (not shown) in the side away from the magazine of a size to permit passage of a container charging rod, to be hereinafter described, thereinto. As is best seen in Figs. 6 and 7, channel 91is positioned relative the magazine byangle iron 94 fixed to the table by bolts 95 and 'to the channel itself by bolts 96. The channel 91 is pref erably angled relative said magazine whereby to position a container opposite an open cavity in the magazine during one of said recovery steps when the magazine isin a fixed position. The interior length and width ofsaid channel 91 is preferably only slightly greater than the length and width of the container to be printed. Fig.7 gives'the best view of the channel 91 showing that the closed end 93 is positioned opposite the cavity 55 in the magazine 54 immediately preceding the one containing the container to be printed in the next printing step. Thus, in viewing the magazine 54 from the front, as in Fig. 7, the cavity to be fed is that in the lower left-hand corner of the magazine.

Charging means are positioned relatives the frontend of said magazine and said feeding means operative to charge a cavity 55 of the magazine 54 during one of said screen rack recovery steps, while the magazine is in stationary position. The charging means preferably comprises a piston rod 97 extending from a pneumatic or bydraulic cylinder 98, said rod extendable and retractable from said pneumatic cylinder 98, thereby to extend into the opening (not shown) in the front surface of the feeding channel 91 to push a container from said feeding means into one of the magazine cavities 55,'as previously described, during one of the screen rack 2'8recovery steps. Pneumatic cylinder 98, as is best seen in Fig. 6, is mounted on brackets 99 and 100 and fixed to the table by bolts 101 and 102 and to the brackets 99 and 100by upper bolts 103 and 104. Pneumatic lines 105 and 106 lead to the cylinder to furnish the impetus for retracting and extending the piston rod 97. The piston rod 97 must be of such length that the motion from its retracted position as shown in Fig. 6 to its extended position is sufiicient to completely force a container from the charinel 91 into the magazine cavity and accurately position traction of thepiston rod 97. relative the. motion of magazine itself and the screen rack and the various other mechanisms involved in the screen printing device. Such timing means are not shown as any desired conventional timing arrangement, either electrical, mechanical, pneumatic, hydraulic or Otherwise will. suffice.

Automatic discharging means are preferably positioned relative said magazine operative to discharge a printed container from onefo f said cavities 55in said magazine 54 after afprinting step. and during one ofsaidf. screen rack recovery steps. The-discharging means is preferably positioned on .the opposite side. of the magazine 55 from said previously described charging-means. Saiddischarging meansis also preferably operable simultaneouslywith as to maintain the endless belt 1'17in extended taut and essentially horizontal relationship therebetween. Wheel 119 adjacent the magazine 54 is: m'ountedon shaft 120 extending rearwardly from the wheel 119. Wheel 119 is Qd to Shaft 120by screw 121 through the hub 122 of the wheel 119, .The shaft 120, is received in upwardly ex tending support. arms "123,'124 and 125; Referring to Fig. 8, pneumatic or hydraulic cylinder 126, having fluid input lines; 127iand 128 thereto, is fixed tothe table '20 by said charging-means whereby to fill one cavity of the I magazine and discharge another during each of said ween, a k: r co y t ps Sa d s h rg n means p erably'comprises a piston rod 107 extending from a pneumatic or hydraulic cylinder 108, said rod 107 extendable from and retractable into said pneumatic cylinder 108 to push a container from oneanother of said cavities 55 during said screen rack recovery step. Pneumatic cylinder 108 is preferably mounted on the rearward side of maga zine 54 as may be seen in Fig. 6, said cylinder being mounted on brackets 109 and 110, respectively, fixed to the table by bolts 111 and 112 and to the top of the brackets by bolts 113 and 114. Pneumatic flow lines 115 and 116 operate to extend and retract the piston rod. The piston rod 107 must be of sufficient length relative the position of the cylinder 108 relative the magazine 54 to force out of the magazine cavity immediately preceding the cavity being chargedtsee Fig. 7 wherein the lower right-hand cavity,fromthe. front viewis being charged during a screen rack recovery step) a printed container. 'I'hisdischarge must, be complete for on the next recovery step, in a four-cavity magazine, the same cavity which was previously scavenged out by the discharging means willbe filled by the charging means piston 97. This cycle is; best seen in Figs. 1 through 5. The diameter of the piston rod 107- is not as critical in this situation as it preferably hits the bottommost end of the container. If

therearmost end of the magazine has been partly closed in the cavity. 55 areas to prevent overshooting of the containers in the charging thereof into the magazine, the piston rod 107 must, of course, be sized so as to enter what opening there is remaining in-the rearmost end of the cavity. Timing means must be provided to simultaneously operate the piston plungers of'the charging and discharging means relative the motion of the screen rack and, again, such timing means are not shown as conven- ,t ional timing means well known in the art may be employed to achieve such desired sequential operation. It is obvious that the spacing of the. hydraulic cylinders 98 and-1 08 and the piston rods 97 and 107 both vertically and horizontally in three dimensions relative the magazine is critical.

Movable means; for individually receiving and suspending. the discharged printed containers by the interior surfaces thereof upon discharge from the magazine by the previously described discharge means are provided positioned relative said magazine. Said receiving means are preferably positioned on the front side of the magazine opposite the discharge means. Means for periodically rnoving-the receiving means coincident with one of the vscreen rack printing steps to remove a loaded individual receiving means for; adjacent said magazine and replace ;whe1els.119z (one. not shown), The-wheels are spaced-"so mounting bracket 12 9 whereby to extend horizontally therealong Piston arm 1 30 extends'from the pneumatic cylinder1126 and engages arm '1311by rotatable bolt 132, the, arml 131'at its] upper end being freely and rotatably mounted on the shaft 120. Rotatably attached to the lower portionof thefront face of upwardly extending arm 131 is pawl or tooth, .133 having spring 134 urging it upwardly and mountingshaft'l35n Fixedly mounted onshaft isvratchet whe,el 136,by screw 137 through hub 138. The retraction and extension of the piston arm from the hydraulic cylinder 126 moves the arm 131 back and forth around its upper encirclement of the shaft 120., Friction disc 139 isfixed to the shaft 120 by screw 140 through the hub 141 forwardly of the second mounting arm 124, the disc being received at its lower edge in friction cylinder 142 having adjustment bolt 143 therethrough and fixed to the table top. 20 by bolt 144. The riction'disc'139 engagement with friction cylinder 1 42 prevents any movement of the shaft 120 with the bacleandforth rotational movement of the arm 131 which isnot fixed to the shaft itself. The tooth of pawl 133 on the front face. ofarm 131,.however, engagesthe ratchet 136. todrive the shaft 120'and sprocket wheel 119 only in counterclockwise rotation as seen from the rear in Big. Stand: clockwise rotation: as seen from theffi'ont in 'Fig. 7. Thus, again looking atthe Fig. 8 rear view, movebetween the ratchet teeth .on ratchet 136, the diameter of the sprocket wheel1119 and the distance between the spikes 118, must be related and adjusted so that asingle extensions-of the rod'130lin each printing step of the screen rack 28 will cause the sprocket wheel 119 to rotate an. angular. distance to. move a loaded, spike. 118 from in front of the: discharge, cavity in the magazine and replace it by another. unloaded spike 118 in exactly the same position. The-frictional disc 139 also prevents overshooting of, this new unloaded spike118 when it arrives in its container receiving position infront of the magazine cavity v to bev discharged. It is evident that the new spike 118 must arrive in front of the container cavity to be discharged. before the. discharging rod 107 is activated during the. rack 28 recovery step so that the spike will be prepared to receive thepreviously printed con tainer. Means are provided engaging at least a portion of the endless beltor chain belt 117 whereby the spikes 118 adjacent the magazine are maintained so as to extend outwardly in an essentially horizontal direction,

thereby always being prepared to receive the printed containers thereon and also whereby the received, printed containers will not depress the spikes by their own grooved member 140 is essentially horizontal and maybe of any desired length between the Wheels 119 driving the endless belt 117 itselfL- 361E142 fixes the horizontal grooved member 140 to the upwardly extending support member 139. It will be seen that the containers which are received individually on each of spikes 118 are afforded time to dry as the endless belt 117 is periodically moved relative the magazine 54. The length of the belt itself, of course, determines the amount of time which is available for drying of the printing on the container itself. The spikes themselves extend essentially as close to the magazine as rear face of the container channel 91 itself so that the discharge piston 107 forces the container almost its full length onto the spikes 118.

In operation, there are six motions of the various operating parts in the silk screen printing apparatus and the container handling inventive means which must be properly coordinated and timed relative one another to accomplish the handling of the containers in the vicinity of the silk screen so they are inserted into the magazine 54, discharged therefrom and received on the spikes 118. The basic movement relative which all of the other operations must be timed is the horizontal movement or motion of the screen rack 28 in its printing and recovery motions. Figs. 1 through 5 illustrate these stages relative the rotation of the magazine 54 and the motion of the filling and discharge plungers 97 and 107 on the charging and discharging pneumatic cylinders. As has previously been described relative the description of the Figs. 1 through 5, the screen rack moves horizontally and transversely of the frame from a starting position in a printing step a predetermined horizontal distance and then returns back to said starting position in a recovery step. The swab 47, which is movable vertically, is down against the screen 29 and magazine and its contents during the printing step and up in the recovery step. The magazine 54 is rotated simultaneously with the horizontal motion of the screen rack and exactly in coincidence therewith in rotational motion by the engagement of the cord 83 with the spool 77 on the magazine mounting shaft 57. As will be seen from Figs. 1 through 3, the four cavity magazine moves one-quarter rotation during the printing step, the diameter of the magazine being such that the circumference of the magazine is four times the length of the printing step. The sprocket wheel 119 is also rotated during the printing step a predetermined distance to move a loaded spike 118 from in front of the discharge cavity position opposite the discharge plunger to position a fresh, unloaded spike thereinfront. The magazine rotation is caused by the pneumatic cylinder 40 drive of the screen rack 28 itself but the rotation of the sprocket wheel.119, as previously described, is caused by the horizontal back and forth motion of the piston rod 130 actuated by the pneumatic or hydraulic cylinder 26 (best seen in Fig. 8). It is necessary, therefore, to time the motion of the piston rod 130 to coincide with the motion of the piston arm 42 of the pneumatic cylinder 40 mounted on the side arm 21. During the recovery step of the screen rack, it is obvious that the magazine itself does not rotate in either direction as is seen in Figs. 3, 4 and 5 and the sprocket wheel 119 itself does not rotate. During the recovery step also, the charging and discharging piston rods 97 and 107, respectively, are fired by their respective pneumatic or hydraulic cylinders 98 and 108, respectively, to charge and discharge adjacent ports of the magazine. The pneumatic cylinders 98 and 108 preferably fire simultaneously. It is evident that the operator must feed containers into the charging chute 91 during the printing step to have a container positioned therein against the closed end 93 when the printing'step is over and the charging plunger is to be fired.

. It is obvious that there are thus only two basic timing problems, namely, the simultaneous actuation of the pneumatic cylinders 40 and 126 to move the screen rack 28 in its printing step and the sprocket wheel 119 in its clearance step and then return the screen rack in its recovery step and the actuating arm 131 of the sprocket shaftto its original position." The second timing problem is to simultaneously actuate the plungers or rods 97 and 107 of the pneumatic cylinders 98 and 108 during the screen rack recovery step. Conventional timing means, either mechanical with cams or electrical with relays, can easily handle such timing sequences and, thus, have not been illustrated. I

Thus it'will be seen that the invention is well adapted to attain the ends and objects hereinbefore set forth, together with other advantages which are obvious and inherent to the construction.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, I claim:

1. Apparatus for handling a plurality of plastic containers in a process of silk screen printing of a portion of the surface of each said container comprising a rotatable magazine having a plurality of spaced cavities extending axially therethrough, each said cavity so formed as to receive and closely confine substantially an entire container, the peripheral portion of each said cavity open to expose an area of a container to be printed positioned therein, means positioned opposite one end of said magazine to feed unprinted containers to a position next said one end of said magazine, a first charging means positioned on the side of said feed means away from the magazine but next the same end of said magazine operative to charge a cavity thereof from said feed means and discharging means positioned next the other end of said magazine from said charging means operative to discharge a container from another cavity of saidmagazine than the one to be charged by said charging means.

2. Apparatus as in claim 1 wherein the means for feeding the containers comprises an enclosed channel having an open end and a closed end, and an opening in the side wall of the channel adjacent to the magazine of a size to permit expulsion of one of said containers therefrom and an opening in the side adjacent the charging means of a size to permit passage of the charging means thereinto.

3. Apparatus as in claim 1 wherein the charging means comprises a pneumatic vessel rod connected to and worked from a pneumatic piston, rod and cylinder assembly, said rod operable to push a container from said feeding means into one of said magazine cavities.

4. Apparatus as in claim 1 wherein said discharging means comprises a pneumatic piston, rod and cylinder assembly, said rod operable to push a container from one of said cavities in said magazine.

5. Apparatus as in claim 1 including movable means for individually receiving and suspending said printed containers by the interior portion thereof upon discharge from said magazine by said discharge means.

6. Apparatus as in claim 5 wherein said movable means comprises an endless belt having a plurality of spikes Refrn'cs Cited in the fil of this patent UNITED STATES PATENTS 1,089,706 Hodge Mai. 10, 1914 1,106,930 Desmond 2 l Aug. 11, 1914 1,336,304 Leumann ;.'2 Apr. 6, 1920 1,574,307 RiSS BI f I- Feb. 23, 1926 I 

